I. Technical Field
The present invention relates generally to electromagnetic interference (EMI) shielding, and more particularly, EMI shielding techniques that reduce the overall amount of space consumed and that offer substantially the same EMI protection as conventional shielding techniques.
II. Background Discussion
Electronic devices are ubiquitous in society and can be found in everything from portable cell phones to wristwatches. Many of these electronic devices either emit electromagnetic interference (EMI) to their surroundings, or are exposed to EMI through their surroundings. Because government regulations often stipulate the amount of EMI that these electronic devices are allowed to emit, the designers of these electronic devices often employ techniques to minimize the amount of EMI emitted from the circuitry within the electronic devices. Additionally, because it is potentially harmful to the circuitry within the electronic devices to be exposed to EMI, the designers of these electronic devices often employ techniques to minimize the amount of EMI to which these electronic devices are exposed. Using EMI shielding techniques, designers minimize both the amount of EMI emitted by and the amount of EMI to which these devices are exposed.
Conventional EMI shielding techniques, sometimes referred to as “frame-and-shield” approaches, often involve encasing circuitry of the electronic device within a metallic structure. The circuitry being encased is mounted, along with other circuitry, on a printed circuit board (PCB). In the frame-and-shield approach, first a metallic frame or “fence” is mounted to the PCB around the periphery of the circuitry that is to be shielded, and then a metallic shield is snap-fit to this fence. While this frame-and-shield approach may limit both the amount of EMI emitted by the circuitry and the amount of EMI to which this circuitry is exposed down to acceptable levels, it also consumes a great deal of space laterally on the PCB and a great deal of space vertically within the electronic device (i.e., in the Z-direction that is generally perpendicular to the surface of the PCB.) This problem is only made worse when the electronic devices have circuitry that is mounted on both sides of the PCB. For example, many portable electronic devices have circuitry located on both the top and bottom of the PCB, and thus, vertical space consumed by EMI shielding techniques is effectively doubled. Accordingly, EMI shielding techniques that reduce the overall amount of space consumed and that offer substantially the same EMI protection as conventional shielding techniques are desirable.